Concept of hide and clear

Question

Problem understanding hide and clear concept...
for example, in the code below, it works fine with the write statement and have no problem with the output value when use the back button.
however, when i use it to call a transaction (eg. mm03) and pass the value over, it seems to be a value behind (eg. when i click on row1, it gives a previously stored value. Press back button and when i click on row2, it gives me value of 1. Press back button and when i click on row5, it gives me value of 2. so the clear doesn't seem to "clear")
what could be the problem? hope to understand this concept of hide and clear better (eg. when to clear?)...
Cheers,
Charles
ABAP newbie
DATA number(18) TYPE c.
START-OF-SELECTION.
  CLEAR number.
  DO 9 TIMES.
    WRITE: / 'Row', (2) sy-index.
    number = sy-index.
    HIDE number.
  ENDDO.
AT PF8.
  CHECK NOT number IS INITIAL.
  CALL TRANSACTION 'MM03'.
  SET PARAMETER ID 'MAT' FIELD number.
  CLEAR number.
*  WRITE: / 'Cursor was in row', (2) NUMBER.

Answer 1

hi,
chk this.
HIDE
Basic form
HIDE f.
In an ABAP Objects context, a more severe syntax check is performed that in other ABAP areas.
See Constants not allowed in HIDE area.
Effect
Retains the contents of f related to the current output line.
When the user selects the line from the list f is automatically filled with the retained value.
The selection can occur in:
AT LINE-SELECTION
AT PFx
AT USER-COMMAND
READ LINE
The contents of the field do not have to have been displayed using WRITE in order for you to retain them.
The HIDE statement does not support deep structures (structures that contain internal tables).
Useful system fields for interactive reporting are listed in the System Fields for Lists documentation.
Note
Lines or components of lines of an internal table that you address using a field symbol (see ASSIGNING addition to the READ and LOOP statements), cannot be retained using HIDE. You can store them using a global variable instead.
Note
Runtime errors:
HIDE_FIELD_TOO_LARGE: The field is too long for HIDE.
HIDE_ON_EMPTY_PAGE: HIDE not possible on an empty page.
HIDE_NO_LOCAL: HIDE not possible for a local field.
HIDE_ILLEGAL_ITAB_SYMBOL: HIDE not possible for a table line or component of a table line.
and also a sample program.
report zxy_0003.
data: begin of itab occurs 0,
field type c,
end of itab.
itab-field = 'A'. append itab.
itab-field = 'B'. append itab.
itab-field = 'C'. append itab.
itab-field = 'D'. append itab.
itab-field = 'E'. append itab.
loop at itab.
format hotspot on.
write:/ itab-field.
hide itab-field.
format hotspot off.
endloop.
at line-selection.
write:/ 'You clicked', itab-field.
It kind of "remembers" what is written, so that when you click on it, it knows what the value is.
Regards,
anver